Reduction of the behavioral response to a viscero-peritoneal nociceptive stimulation during the development of experimental polyarthritis in the rat

Writhing behaviour induced by a viscero-peritoneal nociceptive stimulus (i.p. acetic acid) has been investigated during the development of arthritis experimentally induced in rats by s. c. injection of Mycobacterium butyricum; experiments were carried out at various (1-9 weeks) post-inoculation periods. In the most severe phase (2-5 weeks post-inoculation), when arthritis-induced hyperaesthesia was most pronounced, writhing behaviour was strongly reduced (80%). In the following period, the progressive decrease of hyperaesthesia was contemporaneous with a recovery of the writhing behaviour. We conclude that, in this chronic pain model, the behavioural reaction to a viscero-peritoneal nociceptive stimulus is impaired. Such heterotopic inhibitory processes could be relevant to some paradoxical clinical observations such as the masking of a pain by the experience of pain at another locus (i. e. counter-irritation phenomenon).     

Sequence of a cDNA for mouse thymidylate synthase reveals striking similarity with the prokaryotic enzyme

We report the nucleotide sequence of a cloned cDNA, pMTS-3, that contains a 1-kb insert corresponding to mouse thymidylate synthase (E.C. 2.1.1.45). The open reading frame of 921 nucleotides from the first AUG to the termination codon specifies a protein with a molecular mass of 34,962 daltons. The predicted amino acid sequence is 90% identical with that of the human enzyme. The mouse sequence also has an extremely high degree of similarity (as much as 55% identity) with prokaryotic thymidylate synthase sequences, indicating that thymidylate synthase is among the most highly conserved proteins studied to date. The similarity is especially pronounced (as much as 80% identity) in the 44-amino-acid region encompassing the binding site for deoxyuridylic acid. The cDNA sequence also suggests that mouse thymidylate synthase mRNA lacks a 3' untranslated region, since the termination codon, UAA, is followed immediately by a poly(A) segment.      

Light-modulation of nitrate reductase activity in leaves and roots of maize

The nuclear DNA content in ray cells from the 1-year-old vascular cambium of white ash ( Fraxinus americana L.) trees was determined at intervals during the annual cycle of cambial activity and dormancy by using Feulgen microspectrophotometry. By 10 September, these cells had entered dormancy in G₁ with a normal DNA distribution and a minimal average DNA content of 2.65 pg. The average amount of DNA increased to 3.51 pg by 30 November, remained at this elevated value until at least 30 March, when the cambium was still dormant, then declined to the minimum level on 1 May and 10 June, when the cells were mitotically active. The springtime decline appeared to occur both before and during cell division. Between 1 May and 10 June, the prophase (4C) and telophase (2C) DNA contents decreased significantly. The amount of nuclear DNA measured by microspectrophotometry was verified by using flow cytometry and image analysis. The results support the view that there is an annual oscillation in the nuclear genome size of shoot meristematic cells in tree species native to the northern temperate zone.     

Effect of decreased irradiance on N and C metabolism in leaves and roots of maize

The effects of decreased irradiance on fresh and dry weight, root respiration, levels of carbohydrates and N-compounds, and extractable activities of enzymes involved in C and N metabolism were evaluated in maize ( Zea mays L. cv. Plauto) seedlings during the 7 days following transfer from 450 to 200 μmol m⁻² s⁻¹ PAR. The fresh weight of roots and stems, the initiation of new leaves, root respiration rate, and the accumulation of dry matter, soluble sugars, starch, malate and amino acids in both leaves and roots were strongly reduced at low irradiance. In contrast, the level of nitrate was increased in leaves and only marginally affected in roots. Leaf phosphoenolpyruvate carboxylase (EC 4.1.1.31) activity started to decrease after 24–34 h, whereas ribulose-1,5-bisphosphate carboxylase (EC 4.1.1.39) activity and chlorophyll content were unaffected or only slightly reduced. In both leaves and roots, the adjustment of N metabolism to low irradiance occurred through a relatively rapid (30% after 10 h) and large (60% after 3 days) decrease of nitrate reductase (NR; EC 1.6.6.1) activity, followed by slower and smaller changes in the activity of nitrite reductase (EC 1.7.7.1), glutamine synthetase (EC 6.3.1.2) and NAD-dependent glutamate dehydrogenase (EC 1.4.1.2). We suggest that the preferential decrease of NR activity relative to other N-assimilating enzymes may be important for preventing the accumulation of toxic N-compounds like ammonia in both leaf and root tissues.     

Influence of a natural and a synthetic inhibitor of factor XIIIa on fibrin clot rheology

We investigated the origins of greater clot rigidity associated with FXIIIa-dependent cross-linking. Fibrin clots were examined in which cross-linking was controlled through the use of two inhibitors: a highly specific active-center-directed synthetic inhibitor of FXIIIa, 1,3-dimethyl-4,5-diphenyl-2[2(oxopropyl)thio]imidazolium trifluoromethylsulfonate, and a patient-derived immunoglobulin directed mainly against the thrombin-activated catalytic A subunits of thrombin-activated FXIII. Cross-linked fibrin chains were identified and quantified by one- and two-dimensional gel electrophoresis and immunostaining with antibodies specific for the alpha- and gamma-chains of fibrin. Gamma-dimers, gamma-multimers, alpha(n)-polymers, and alpha(p)gamma(q)-hybrids were detected. The synthetic inhibitor was highly effective in preventing the production of all cross-linked species. In contrast, the autoimmune antibody of the patient caused primarily an inhibition of alpha-chain cross-linking. Clot rigidities (storage moduli, G') were measured with a cone and plate rheometer and correlated with the distributions of the various cross-linked species found in the clots. Our findings indicate that the FXIIIa-induced dimeric cross-linking of gamma-chains by itself is not sufficient to stiffen the fibrin networks. Instead, the augmentation of clot rigidity was more strongly correlated with the formation of gamma-multimers, alpha(n)-polymers, and alpha(p)gamma(q)-hybrid cross-links. A mechanism is proposed to explain how these cross-linked species may enhance clot rigidity.     

大鼠放射性肺损伤模型的建立与动态观察

目的：建立并鉴定大鼠放射性肺损伤模型,摸索大鼠放射性肺损伤的病理变化规律,阐明氧化应激在其发生发展过程中的作用。方法：采用60Co源22Gy单次照射SD大鼠全肺。分别于照射前、照后1天,7天,15天,21天,30天,60天,120天活杀大鼠,计算肺系数,右肺行HE染色、Masson染色及天狼猩红染色,观察肺组织病理变化并对大鼠肺泡炎及纤维化程度进行评分,免疫组化法检测肺组织廿SMA表达情况;左肺进行羟脯氨酸含量测定;血清测定MDA含量、总SOD活力和TGF-β1含量。结果：（1）大鼠肺脏于照后15天开始出现明显大体改变,病理学表现为间质性渗出性炎症并随时间延长逐渐加重,照后60天至120天肺脏塌陷,表面可见纤维化病灶,病理改变以肺间隔内细胞增生和胶原纤维沉积为主;（2）血清T-SOD活力照后1天至7天短暂增加后其活力持续降低;血清MDA含量和TGF-β1含量随时间时间延长逐渐增高;（3）照后60天肺组织a-SMA表达明显增加,至照后120天最为显著。结论：成功建立了大鼠放射性肺损伤模型并阐述了其病理变化规律;氧化应激参与了放射性肺损伤的病理过程。为其防治提供了实验基础和理论依据。     

Historical trends in frog populations in New Zealand based on public perceptions

Surveys were distributed to New Zealand land users in 1998 and 2008 to acquire information about New Zealand frogs with the aim of compiling and mapping their distribution and inferred population trends without costly and time-consuming field surveys. The overall frog population trend was reported as declining, with possible causes reported as an increase in agriculture, an increase in the distribution of predatory fish and disease. The resultant maps could be used for four main purposes: 1) to identify regions where Litoria populations are known to occur, which can be eliminated when considering suitable regions for translocation of Leiopelma; 2) to identify growing or stable populations of Litoria species, which may assist future disease surveys, population monitoring and to identify sources of genetic material that may serve as an Ark for declining Australian populations; 3) to highlight populations that are in decline to enable effective targeting of detailed disease studies; and 4) to approximate the stability of amphibian populations in the absence of more accurate, but costly, scientific monitoring.